"content":"<p>Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (<code>push</code>, <code>peek</code>, <code>pop</code>, and <code>empty</code>).</p>\n\n<p>Implement the <code>MyQueue</code> class:</p>\n\n<ul>\n\t<li><code>void push(int x)</code> Pushes element x to the back of the queue.</li>\n\t<li><code>int pop()</code> Removes the element from the front of the queue and returns it.</li>\n\t<li><code>int peek()</code> Returns the element at the front of the queue.</li>\n\t<li><code>boolean empty()</code> Returns <code>true</code> if the queue is empty, <code>false</code> otherwise.</li>\n</ul>\n\n<p><strong>Notes:</strong></p>\n\n<ul>\n\t<li>You must use <strong>only</strong> standard operations of a stack, which means only <code>push to top</code>, <code>peek/pop from top</code>, <code>size</code>, and <code>is empty</code> operations are valid.</li>\n\t<li>Depending on your language, the stack may not be supported natively. You may simulate a stack using a list or deque (double-ended queue) as long as you use only a stack's standard operations.</li>\n</ul>\n\n<p> </p>\n<p><strong class=\"example\">Example 1:</strong></p>\n\n<pre>\n<strong>Input</strong>\n["MyQueue", "push", "push", "peek", "pop", "empty"]\n[[], [1], [2], [], [], []]\n<strong>Output</strong>\n[null, null, null, 1, 1, false]\n\n<strong>Explanation</strong>\nMyQueue myQueue = new MyQueue();\nmyQueue.push(1); // queue is: [1]\nmyQueue.push(2); // queue is: [1, 2] (leftmost is front of the queue)\nmyQueue.peek(); // return 1\nmyQueue.pop(); // return 1, queue is [2]\nmyQueue.empty(); // return false\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 <= x <= 9</code></li>\n\t<li>At most <code>100</code> calls will be made to <code>push</code>, <code>pop</code>, <code>peek</code>, and <code>empty</code>.</li>\n\t<li>All the calls to <code>pop</code> and <code>peek</code> are valid.</li>\n</ul>\n\n<p> </p>\n<p><strong>Follow-up:</strong> Can you implement the queue such that each operation is <strong><a href=\"https://en.wikipedia.org/wiki/Amortized_analysis\" target=\"_blank\">amortized</a></strong> <code>O(1)</code> time complexity? In other words, performing <code>n</code> operations will take overall <code>O(n)</code> time even if one of those operations may take longer.</p>\n",
"code":"class MyQueue {\npublic:\n MyQueue() {\n \n }\n \n void push(int x) {\n \n }\n \n int pop() {\n \n }\n \n int peek() {\n \n }\n \n bool empty() {\n \n }\n};\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * MyQueue* obj = new MyQueue();\n * obj->push(x);\n * int param_2 = obj->pop();\n * int param_3 = obj->peek();\n * bool param_4 = obj->empty();\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Java",
"langSlug":"java",
"code":"class MyQueue {\n\n public MyQueue() {\n \n }\n \n public void push(int x) {\n \n }\n \n public int pop() {\n \n }\n \n public int peek() {\n \n }\n \n public boolean empty() {\n \n }\n}\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * MyQueue obj = new MyQueue();\n * obj.push(x);\n * int param_2 = obj.pop();\n * int param_3 = obj.peek();\n * boolean param_4 = obj.empty();\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Python",
"langSlug":"python",
"code":"class MyQueue(object):\n\n def __init__(self):\n \n\n def push(self, x):\n \"\"\"\n :type x: int\n :rtype: None\n \"\"\"\n \n\n def pop(self):\n \"\"\"\n :rtype: int\n \"\"\"\n \n\n def peek(self):\n \"\"\"\n :rtype: int\n \"\"\"\n \n\n def empty(self):\n \"\"\"\n :rtype: bool\n \"\"\"\n \n\n\n# Your MyQueue object will be instantiated and called as such:\n# obj = MyQueue()\n# obj.push(x)\n# param_2 = obj.pop()\n# param_3 = obj.peek()\n# param_4 = obj.empty()",
"__typename":"CodeSnippetNode"
},
{
"lang":"Python3",
"langSlug":"python3",
"code":"class MyQueue:\n\n def __init__(self):\n \n\n def push(self, x: int) -> None:\n \n\n def pop(self) -> int:\n \n\n def peek(self) -> int:\n \n\n def empty(self) -> bool:\n \n\n\n# Your MyQueue object will be instantiated and called as such:\n# obj = MyQueue()\n# obj.push(x)\n# param_2 = obj.pop()\n# param_3 = obj.peek()\n# param_4 = obj.empty()",
"code":"public class MyQueue {\n\n public MyQueue() {\n \n }\n \n public void Push(int x) {\n \n }\n \n public int Pop() {\n \n }\n \n public int Peek() {\n \n }\n \n public bool Empty() {\n \n }\n}\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * MyQueue obj = new MyQueue();\n * obj.Push(x);\n * int param_2 = obj.Pop();\n * int param_3 = obj.Peek();\n * bool param_4 = obj.Empty();\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"JavaScript",
"langSlug":"javascript",
"code":"\nvar MyQueue = function() {\n \n};\n\n/** \n * @param {number} x\n * @return {void}\n */\nMyQueue.prototype.push = function(x) {\n \n};\n\n/**\n * @return {number}\n */\nMyQueue.prototype.pop = function() {\n \n};\n\n/**\n * @return {number}\n */\nMyQueue.prototype.peek = function() {\n \n};\n\n/**\n * @return {boolean}\n */\nMyQueue.prototype.empty = function() {\n \n};\n\n/** \n * Your MyQueue object will be instantiated and called as such:\n * var obj = new MyQueue()\n * obj.push(x)\n * var param_2 = obj.pop()\n * var param_3 = obj.peek()\n * var param_4 = obj.empty()\n */",
"code":"class MyQueue {\n constructor() {\n \n }\n\n push(x: number): void {\n \n }\n\n pop(): number {\n \n }\n\n peek(): number {\n \n }\n\n empty(): boolean {\n \n }\n}\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * var obj = new MyQueue()\n * obj.push(x)\n * var param_2 = obj.pop()\n * var param_3 = obj.peek()\n * var param_4 = obj.empty()\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"PHP",
"langSlug":"php",
"code":"class MyQueue {\n /**\n */\n function __construct() {\n \n }\n \n /**\n * @param Integer $x\n * @return NULL\n */\n function push($x) {\n \n }\n \n /**\n * @return Integer\n */\n function pop() {\n \n }\n \n /**\n * @return Integer\n */\n function peek() {\n \n }\n \n /**\n * @return Boolean\n */\n function empty() {\n \n }\n}\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * $obj = MyQueue();\n * $obj->push($x);\n * $ret_2 = $obj->pop();\n * $ret_3 = $obj->peek();\n * $ret_4 = $obj->empty();\n */",
"code":"class MyQueue() {\n\n fun push(x: Int) {\n \n }\n\n fun pop(): Int {\n \n }\n\n fun peek(): Int {\n \n }\n\n fun empty(): Boolean {\n \n }\n\n}\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * var obj = MyQueue()\n * obj.push(x)\n * var param_2 = obj.pop()\n * var param_3 = obj.peek()\n * var param_4 = obj.empty()\n */",
"code":"class MyQueue() {\n\n def push(x: Int) {\n \n }\n\n def pop(): Int = {\n \n }\n\n def peek(): Int = {\n \n }\n\n def empty(): Boolean = {\n \n }\n\n}\n\n/**\n * Your MyQueue object will be instantiated and called as such:\n * var obj = new MyQueue()\n * obj.push(x)\n * var param_2 = obj.pop()\n * var param_3 = obj.peek()\n * var param_4 = obj.empty()\n */",
"code":"-spec my_queue_init_() -> any().\nmy_queue_init_() ->\n .\n\n-spec my_queue_push(X :: integer()) -> any().\nmy_queue_push(X) ->\n .\n\n-spec my_queue_pop() -> integer().\nmy_queue_pop() ->\n .\n\n-spec my_queue_peek() -> integer().\nmy_queue_peek() ->\n .\n\n-spec my_queue_empty() -> boolean().\nmy_queue_empty() ->\n .\n\n\n%% Your functions will be called as such:\n%% my_queue_init_(),\n%% my_queue_push(X),\n%% Param_2 = my_queue_pop(),\n%% Param_3 = my_queue_peek(),\n%% Param_4 = my_queue_empty(),\n\n%% my_queue_init_ will be called before every test case, in which you can do some necessary initializations.",
"code":"defmodule MyQueue do\n @spec init_() :: any\n def init_() do\n \n end\n\n @spec push(x :: integer) :: any\n def push(x) do\n \n end\n\n @spec pop() :: integer\n def pop() do\n \n end\n\n @spec peek() :: integer\n def peek() do\n \n end\n\n @spec empty() :: boolean\n def empty() do\n \n end\nend\n\n# Your functions will be called as such:\n# MyQueue.init_()\n# MyQueue.push(x)\n# param_2 = MyQueue.pop()\n# param_3 = MyQueue.peek()\n# param_4 = MyQueue.empty()\n\n# MyQueue.init_ will be called before every test case, in which you can do some necessary initializations.",
"envInfo":"{\"cpp\": [\"C++\", \"<p>Compiled with <code> clang 11 </code> using the latest C++ 20 standard.</p>\\r\\n\\r\\n<p>Your code is compiled with level two optimization (<code>-O2</code>). <a href=\\\"https://github.com/google/sanitizers/wiki/AddressSanitizer\\\" target=\\\"_blank\\\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\"], \"java\": [\"Java\", \"<p><code>OpenJDK 17</code>. Java 8 features such as lambda expressions and stream API can be used. </p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\\r\\n<p>Includes <code>Pair</code> class from https://docs.oracle.com/javase/8/javafx/api/javafx/util/Pair.html.</p>\"], \"python\": [\"Python\", \"<p><code>Python 2.7.12</code>.</p>\\r\\n\\r\\n<p>Most libraries are already imported automatically for your convenience, such as <a href=\\\"https://docs.python.org/2/library/array.html\\\" target=\\\"_blank\\\">array</a>, <a href=\\\"https://docs.python.org/2/library/bisect.html\\\" target=\\\"_blank\\\">bisect</a>, <a href=\\\"https://docs.python.org/2/library/collections.html\\\" target=\\\"_blank\\\">collections</a>. If you need more libraries, you can import it yourself.</p>\\r\\n\\r\\n<p>For Map/TreeMap data structure, you may use <a href=\\\"http://www.grantjenks.com/docs/sortedcontainers/\\\" target=\\\"_blank\\\">sortedcontainers</a> library.</p>\\r\\n\\r\\n<p>Note that Python 2.7 <a href=\\\"https://www.python.org/dev/peps/pep-0373/\\\" target=\\\"_blank\\\">will not be maintained past 2020</a>. For the latest Python, please choose Python3 instead.</p>\"], \"c\": [\"C\", \"<p>Compiled with <code>gcc 8.2</code> using the gnu11 standard.</p>\\r\\n\\r\\n<p>Your code is compiled with level one optimization (<code>-O1</code>). <a href=\\\"https://github.com/google/sanitizers/wiki/AddressSanitizer\\\" target=\\\"_blank\\\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\\r\\n\\r\\n<p>For hash table operations, you may use <a href=\\\"https://troydhanson.github.io/uthash/\\\" target=\\\"_blank\\\">uthash</a>. \\\"uthash.h\\\" is included by default. Below are some examples:</p>\\r\\n\\r\\n<p><b>1. Adding an item to a hash.</b>\\r\\n<pre>\\r\\nstruct hash_entry {\\r\\n int id; /* we'll use this field as the key */\\r\\n char name[10];\\r\\n UT_hash_handle hh; /* makes this structure hashable */\\r\\n};\\r\\n\\r\\nstruct hash_entry *users = NULL;\\r\\n\\r\\nvoid add_user(struct hash_entry *s) {\\r\\n HASH_ADD_INT(users, id, s);\\r\\n}\\r\\n</pre>\\r\\n</p>\\r\\n\\r\\n<p><b>2. Looking up an item in a hash:</b>\\r\\n<pre>\\r\\nstruct hash_entry *find_user(int user_id) {\\r\\n struct hash_entry *s;\\r\\n HASH_FIND_INT(users, &user_id, s);\\r\\n return s;\\r\\n}\\r\\n</pre>\\r\\n</p>\\r\\n\\r\\n<p><b>3. Deleting an item in a hash:</b>\\r\\n<pre>\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n HASH_DEL(users, user); \\r\\n}\\r\\n</pre>\\r\\n</p>\"], \"csharp\": [\"C#\", \"<p><a href=\\\"https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-10\\\" target=\\\"_blank\\\">C# 10 with .NET 6 runtime</a></p>\"], \"javascript\": [\"JavaScript\", \"<p><code>Node.js 16.13.2</code>.</p>\\r\\n\\r\\n<p>Your code is run with <code>--harmony</code> flag, enabling <a href=\\\"http://node.green/\\\" target=\\\"_blank\\\">new ES6 features</a>.</p>\\r\\n\\r\\n<p><a href=\\\"https://lodash.com\\\" target=\\\"_blank\\\">lodash.js</a> library is included by default.</p>\\r\\n\\r\\n<p>For Priority Queue / Queue data structures, you may use 5.3.0 version of <a href=\\\"https://github.com/datastructures-js/priority-queue/tree/fb4fdb984834421279aeb081df7af624d17c2a03\\\" target=\\\"_blank\\\">datastructures-js/priority-queue</a> and 4.2.1 version of <a href=\\\"https://githu
